At the present time there are approximately 131 million streetlights and outdoor area lights in the USA. If all of those lights were turned off for an additional minute per day, 250,000,000 lb CO2 would be prevented from entering the atmosphere per year and result in $79,000,000 in yearly energy savings.
Current street light controllers are constructed and arranged to switch the street lights on and off by detection of ambient light or by the use of a conventional clock timer. Turning off a street light when ambient light is available reduces unnecessary energy consumption and extends the life of the street light. The existing controllers that detect light implement photoresistors that absorb photons at a particular wavelength. As the sun rises the number of photons absorbed increases and the controller will turn off the street light at a predetermined absorption rate.
Although photoresistor light switches exist, the use of photoresistors has numerous shortcomings. For instance, photoresistors decay over time resulting in unreliable light switches. As described supra, photoresistor decay that disrupts the timing of the implemented light switches by even a minute can cost millions of dollars per year in lost energy.
An additional shortcoming occurs because photoresistor light switches include a housing with a window that protect the electrical components from bearing the elements, the window permits photons to pass through the housing and strike the photoresistor. In many cases, the window accumulates dirt or other impediments such as snow or lens discoloration that inhibits photons from reaching the photoresistor, thereby decreasing the effectiveness of the photoresistor. In addition, the window must be pointed in a particular direction.
Furthermore, photoresistors are inefficient consumers of electricity.